Need help fast lads.....

problem guys i need help i recently got a real problem one minute one of my plants was ok then the next day i checked it i saw that it was drying up and the top leaves on the top of the colas started to wilt aand go yellow but the day before it was looking really nice so i removed the dead leaves from the top and bottom of the plant then the next day it had spread to the other colas and now it looks like the plants actually dying this is on its 7th week of flowering just about give or take a day can anyone help i dont know the plant as it was in a bag i bought from a friend but the other 3 plants are doing great and these 3 are cheese from nirvana all fems and looking good anyone got any idea whats happened...hydro all the way btw i dont use any added nutes other than aqua flower as this is my 1st grow to see how it goes theyre levels are all fine and vent and all thats fine.

You have a lot of leaf wilt and what looks like either nute burn or a pH imbalance. Have you checked all of your equipment to make it is all working properly?

ye everything is fine ph is about 5.8, 6.0 says to keep it around that level on the aqua flores container so i have done since flowering about 7 weeks ago and no problem up until now.

How do the roots look on that plant?

when was the last time you calibrated your meter?

the roots look fine no discolouring or burning or brown bits they just look like the other 3 plants thats in the same hydro and i dont use meter stick i use a test card that has the spectrum on it and the correct ph levels which is really accurate.

So what exactly are you feeding it? And you often are you watering?
And what is the temperature at canopy level (directly under the light)?

em im using aqua flores A,B 30ml to 10l of water and im keeping the ph to 5.8 or around there im watering them 3,4 times a day for 45 mins i water them manulay through my pump as im constantly in at them everyday so i wait until they go dry then water them again then turn the pump off after 45 mins.just seems funny how its just this plant and theother 3 are ok mind you this ones a different species the other 3 are swiss cheese and they can take a bit of stress.my temps are fine imve got a cooltube and even at thats its a good 16,18 inches away.